The invention relates to a wheel for a motorcycle or motor scooter, in particular to a rear wheel of a motorcycle or a motor scooter.
For reasons of weight saving, there is an effort to use lighter components in motor vehicles. In recent years, fiber-reinforced plastics increasingly have been used.
This concept is also implemented in motorcycle wheels. Here, rims and spokes can be manufactured completely from fiber-reinforced plastic, in particular from carbon fiber-reinforced plastic. Two metallic inserts have been embedded up to now into the fiber-reinforced plastic on axially opposite sides of the wheel in the hub region to introduce force from a drive sprocket on the one wheel side and from a brake disk on the other wheel side. The two inserts are spaced apart from one another and inserted separately from both sides of the wheel.
The conventionally used fiber-reinforced plastics are designed only for a certain maximum temperature. However, high temperatures can also occur for relatively long times during braking maneuvers precisely at the brake disk-side insert, with the result that additional heat dissipation has to be ensured.
It is an object of the invention to provide a wheel which is as light as possible and as temperature-insensitive as possible.
According to the invention, this is achieved in a wheel for a motorcycle or a motor scooter, which wheel consists at least in sections of a fiber-reinforced plastic, a hub region of the wheel having two rigid, self-supporting, metallic inserts which are arranged on axially opposite sides of the hub region and which are connected to one another in a positively locking manner in the axial and radial direction.
Due to the positively locking connection of the two inserts, a rapid transfer of thermal energy also takes place in the axial direction from the brake disk-side insert to the opposite side of the wheel to the second insert. This results in an improved distribution of the thermal energy, and the additional surface area of the second insert, moreover, results in an improved dissipation of the thermal energy. As a result of the transfer of heat to the second insert, more uniform heating of the hub region of the wheel also takes place, with the result that more uniform loading of the fiber-reinforced plastic sections as a result of the action of heat occurs.
In addition, the positively locking engagement of the two inserts which lie on opposite sides of the wheel ensures a coaxial orientation of the force introduction points of both inserts with regard to the wheel axis and therefore a correct orientation of the entire hub region in a simple way. The force introduction points can be formed, for example, by way of openings in the respective insert.
As in the case of known wheels, one of the inserts is designed for fastening a brake disk and/or the other insert is designed for fastening a drive sprocket. The fastening of the drive sprocket and/or brake disk can take place via the openings in the inserts. The invention can be used both in rear wheels and in front wheels, it not being necessary for a drive sprocket to be provided in the case of the use as a front wheel.
The two inserts can be connected to the surrounding fiber composite of the fiber-reinforced plastic sections of the wheel, for example, by way of being pressed in, adhesively bonded or laminated in, it additionally optionally being possible for the plastic to also engage into recesses on the insert.
The fiber-reinforced plastic is, for example, a carbon fiber-reinforced plastic (CRP). It goes without saying that other suitable fibers can also be used for reinforcement.
With the exception of the inserts and of course a tire, the wheel can consist substantially completely of fiber-reinforced plastic. Further metallic constituent parts next to the two inserts are normally not provided in the hub region.
The sections of the two inserts which form the axial positively locking connection preferably lie substantially in the axial center of the two inserts.
In order to form the positively locking connection, at least one of the inserts can have at least one circumferential, axially extending limb which, at its free end, bears against a bearing section of the other insert.
A shoulder which produces an axial and a radial stop is configured, for example, at the free end of the limb and/or on the bearing section, with the result that, when the inserts bear against one another, a positively locking connection is produced in the axial and radial direction. During the assembly of the inserts during the manufacture of the wheel, the inserts thus assume their correct final assembly position in the axial and radial direction in a simple way. Here, centering of the force introduction points of both inserts is also ensured automatically.
In one preferred embodiment, each insert has two circumferential, coaxial, axially extending limbs, a bearing section being configured on each of the pairs of limbs which lie opposite one another, in each case on one of the limbs. In one possible variant, both bearing sections are provided on the same insert.
Each of the bearing sections can have a shoulder, the shoulders of the two bearing sections preferably being of mirror-symmetrical configuration with regard to the radial direction, in order to achieve secure fixing in the radial direction. In this case, the free ends of the limbs of the one insert are pushed, for example, onto the bearing sections in such a way that the free ends engage around them radially. Using a geometry of this type, both the radial and the axial positively locking connection can be produced simply by way of the two inserts being pushed together axially.
The ends which lie opposite the free ends of the limbs are preferably connected in each insert via an annular disk which extends, for example, perpendicularly with respect to the axial direction.
In the region of the positively locking connection, the two inserts do not have to be connected fixedly to one another, but rather can be held in their position via the embedding into the sections of the wheel made from fiber-reinforced plastic.
A positively locking and non-positive connection is preferably also formed in the circumferential direction between the two inserts. This has the advantage that acceleration forces, both during the increase in the vehicle speed via the drive sprocket and during the retardation of the two-wheeled vehicle via the brake disk, are always transmitted uniformly to both inserts, which increases the stability of the overall wheel. Here, the positively locking and non-positive connection in the circumferential direction ensures a uniform introduction of force into the overall hub region of the wheel.
In order to produce the positively locking and non-positive connection in the circumferential direction, complementary toothing systems which engage into one another can be configured, for example, on at least one radial outer side of one of the inserts and on at least one radial inner side of the other insert. The toothing systems are preferably provided in each case at all free ends of the limbs and on all bearing sections of both inserts which engage into one another for the axial positively locking connection.
Both inserts advantageously together enclose a toroidal cavity, both in order to save weight and also in order to increase the stability of the wheel. The cavity can be configured between the limbs which run in the axial direction and the annular disks of the two inserts.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.